Aerogel-based electrodes

ABSTRACT

Electrodes, production methods and mono-cell batteries are provided, which comprise active material particles embedded in electrically conductive metallic porous structure, dry-etched anode structures and battery structures with thick anodes and cathodes that have spatially uniform resistance. The metallic porous structure provides electric conductivity, a large volume that supports good ionic conductivity, that in turn reduces directional elongation of the particles during operation, and may enable reduction or removal of binders, conductive additives and/or current collectors to yield electrodes with higher structural stability, lower resistance, possibly higher energy density and longer cycling lifetime. Dry etching treatments may be used to reduce oxidized surfaces of the active material particles, thereby simplifying production methods and enhancing porosity and ionic conductivity of the electrodes. Electrodes may be made thick and used to form mono-cell batteries which are simple to produce and yield high performance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 16/254,632, filed on Jan. 23, 2019, which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to the field of energy storage devices,and more particularly, to lithium ion batteries and electrodes thereof.

2. Discussion of Related Art

Energy storage devices, and particularly rechargeable batteries such aslithium ion batteries, are in high demand and continue to presentperformance and safety challenges. Lithium ion batteries are used for agrowing range of applications, as their capacity and charging rates areincreased. For example, metalloid-based anode materials such as Si, Ge,Sn and combinations thereof are used to deliver high performance lithiumion batteries.

SUMMARY OF THE INVENTION

The following is a simplified summary providing an initial understandingof the invention. The summary does not necessarily identify key elementsnor limit the scope of the invention, but merely serves as anintroduction to the following description.

One aspect of the present invention provides an electrode comprisingactive material particles embedded in electrically conductive metallicporous structure.

One aspect of the present invention provides an electrode comprisingactive material particles embedded in an electrically conductivemetallic aerogel, wherein the electrode is part of a fast-charginglithium ion cell that is configured to be operated at a maximal chargingrate of 4C or higher, and the active material particles are configuredto incorporate and release lithium ions.

One aspect of the present invention provides a method of preparing ananode for a lithium ion battery, the method comprising: preparing a rawanode from oxidized active material particles and a porous supportingstructure that includes electron conductive elements and pores thatinterconnect the oxidized active material particles among themselves andto a surface of the raw anode, and applying a dry etching treatment tothe raw anode to at least partly reduce the oxidized active materialparticles through the pores and yield the anode in an operable state.

One aspect of the present invention provides a mono-cell batterycomprising at least one anode and at least one cathode separated by atleast one separator or by a semi-solid electrolyte, wherein the anodeand the cathode comprise corresponding anode and cathode active materialparticles embedded in respective electrically conductive metallic porousstructures.

These, additional, and/or other aspects and/or advantages of the presentinvention are set forth in the detailed description which follows;possibly inferable from the detailed description; and/or learnable bypractice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the invention and to showhow the same may be carried into effect, reference will now be made,purely by way of example, to the accompanying drawings in which likenumerals designate corresponding elements or sections throughout.

In the accompanying drawings:

FIGS. 1A and 1B are high-level schematic illustrations of the structureof a section of an electrode, according to some embodiments of theinvention.

FIGS. 2A and 2B are high-level schematic illustrations of the use ofcathode material primary nanoparticles, according to some embodiments ofthe invention, instead of prior art secondary conglomerates thereof.

FIGS. 3A and 3B are high-level schematic illustration of prior artelectrodes with active material particles embedded in binder material.

FIG. 4 is a high-level schematic block diagram of systems for anodepreparation and for preparing mono-cell batteries, according to someembodiments of the invention.

FIGS. 5A and 5B are schematic high-level illustrations of a raw anode inschematic cross-section and a RIE (reactive-ion etching) plasmatreatment application that yields prepared anode, respectively,according to some embodiments of the invention.

FIGS. 5C-5F are schematic high-level illustrations of raw anodes inschematic cross-section and dry etching treatment application thatyields prepared anodes, according to some embodiments of the invention.

FIGS. 6A and 6B are high-level illustrations of batteries, according tosome embodiments of the invention.

FIGS. 7A and 7B are high-level schematic illustrations of mono-cellbatteries, according to some embodiments of the invention, compared withprior art battery configurations illustrated schematically in FIGS. 7Cand 7D.

FIGS. 7C and 7D represent prior art battery configurations.

FIGS. 8B-8E are high-level schematic illustrations of cylindrical celldesigns according to some embodiments of the invention, compared withprior art cylindrical cell design illustrated in FIG. 8A.

FIG. 9 is a high-level flowchart illustrating a method, according tosome embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, various aspects of the present inventionare described. For purposes of explanation, specific configurations anddetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will also be apparent to one skilledin the art that the present invention may be practiced without thespecific details presented herein. Furthermore, well known features mayhave been omitted or simplified in order not to obscure the presentinvention. With specific reference to the drawings, it is stressed thatthe particulars shown are by way of example and for purposes ofillustrative discussion of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

Before at least one embodiment of the invention is explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention is applicable to other embodiments that may bepracticed or carried out in various ways as well as to combinations ofthe disclosed embodiments. Also, it is to be understood that thephraseology and terminology employed herein are for the purpose ofdescription and should not be regarded as limiting.

Embodiments of the present invention provide efficient and economicalmethods and mechanisms for preparing electrodes, e.g., anodes, andthereby provide improvements to the technological field of energystorage devices.

Electrodes, production methods and batteries are provided, whichcomprise active material particles embedded in electrically conductivemetallic porous structure. Anodes may comprise metalloid, metal and/orcarbon-based anode active material particles in e.g., copper, nickeland/or titanium, their combinations and/or their alloy aerogel/foam,while cathodes may comprise any type of cathode material which may beembedded as primary nanoparticles (rather than prior art secondaryconglomerates thereof) in aluminum or nickel or stainless-steel, theircombinations and/or their alloy aerogel/foam. The metallic porousstructure provides electric conductivity, a large volume that supportsgood ionic conductivity, that in turn reduces directional elongation ofthe particles during operation, and may enable reduction or removal ofbinders, conductive additives and/or current collectors to yieldelectrodes with higher structural stability, lower resistance, possiblyhigher energy density and longer cycling lifetime. Production may befacilitated by mixing active material particle slurry with aerogeland/or foam precursors, or binding the active material particles intothe prepared metallic porous structure.

Systems and methods of preparing an anode for a lithium ion battery areprovided. After preparing a raw anode from oxidized active materialparticles and a porous supporting structure that includes electronconductive elements and pores (and/or pores as ion conductive paths)that interconnect the oxidized active material particles amongthemselves and to a surface of the raw anode—a dry etching treatment isapplied to the raw anode to at least partly reduce the oxidized activematerial particles through the pores to yield the anode in an operablestate. Advantageously, the reduction (de-oxidation) is performed at thesurface areas of the particles which contact the pores, to establishgood ion conductivity of the anode.

Electrodes, production methods and mono-cell batteries are provided,which comprise active material particles embedded in electricallyconductive metallic porous structure, dry-etched anode structures andbattery structures with thick anodes and cathodes that have spatiallyuniform resistance. The metallic porous structure provides electricconductivity, a large volume that supports good ionic conductivity, thatin turn reduces directional elongation of the particles duringoperation, and may enable reduction or removal of binders, conductiveadditives and/or current collectors to yield electrodes with higherstructural stability, lower resistance, possibly higher energy densityand longer cycling lifetime. Dry etching treatments may be used toreduce oxidized surfaces of the active material particles, therebysimplifying production methods and enhancing porosity and ionicconductivity of the electrodes. Electrodes may be made thick and used toform mono-cell batteries which are simple to produce and yield highperformance, low resistance, uniform cell parameters and higher energydensity.

FIGS. 1A and 1B are high-level schematic illustrations of the structureof a section of an electrode 100, according to some embodiments of theinvention. Electrode 100 comprises active material particles 120embedded in electrically conductive metallic porous structure 110, suchas aerogel and/or foam 110. FIG. 1A illustrates schematically, in anon-limiting manner the use of aerogel 110 while FIG. 1B illustratesschematically, in a non-limiting manner the use of foam 110. Metallicporous structure 110 may have various structural configurations, such asaerogels comprising an anisotropic assembly of wires or needles at avery small scale (e.g., having widths of few to tens of nanometers andlengths of tens or hundreds of nanometers to few micrometers) and/ordried foams such as open-cell foams comprising an anisotropic assemblyof cell walls or parts thereof at a very small scale (e.g., having wallthicknesses of few to tens of nanometers). During operation (and/orpossibly during formation) 102 of electrode 100, some structuraldeformation 123 of particles 120 may occur due to lithiation andde-lithiation of particles 120 which are accompanied by mechanicalexpansion and contraction, respectively, of particles 120. As most ofthe surrounding of particles 120 is ionic conductive, structuraldeformation 123 are expected to be relatively uniform in differentdirections (essentially isotropic), because lithium ions (Li⁺) can enterand exit particles 120 over a wide range of spatial directions, asillustrated schematically in the enlarged portion of FIG. 1 . Moreover,the limited extent of structural deformation 123 may be beneficial inanchoring particles 120 within metallic porous structure matrix 110,enhancing the mechanical stability of electrode 100.

Aerogels and/or foams 110 comprise highly porous, anisotropic solids,which may be made of electrically conductive materials, e.g., any ofaluminum, nickel, copper, titanium, gold, stainless steel, theircombinations and/or their alloys. Embedding active material particles120 in electrically conductive metallic porous structure 110 providesseveral benefits, including light weight of the electrodes, reduction orelimination of prior art binders, good contact to (or replacement of)the current collector, high electric conductivity of the aerogel and/orfoam material and high ionic conductivity resulting from the porosity ofthe aerogel structure. Moreover, as the aerogel is anisotropic, theirregular structure mechanically prevents excessive elongation of activematerial particles 120 in any specific direction. Foam 110 may compriseany three-dimensional metal foam. The thickness, density, structure andpore sizes may be optimized for the application, type of particles,solvent used for particles' deposition, total foil (current collector)resistance and other parameters of electrode 100. Advantageously, thedeformation of active material particles 120 anchors them stronger intosurrounding metallic porous structure 110 and enhances the mechanicalstability of electrode 100.

In certain embodiments, electrode 100 may comprise an anode of a lithiumion cell (e.g., a fast-charging lithium ion cell) and active materialparticles 120 may be anode active material particles. For example, anodeactive material particles 120 may comprise metalloids such as Si, Geand/or Sn particles 120 and/or particles 120 comprising alloys and/ormixtures of Si, Ge and/or Sn, possibly with additional materials such asforms of carbon. Anode active material particles 120 may be at leastpartly coated and/or at least partly oxidized. In certain embodiments,anode active material particles 120 may comprise metallic particles suchas Mn-based and/or Fe-based particles, and/or carbon-based particlesthat include e.g., graphene and/or graphite. Certain embodimentscomprise any combination of anode active materials disclosed above, suchas metalloid, metal and carbon-based particles. In case of anodes,metallic porous structure 110 may comprise copper, nickel and/ortitanium, their combinations and/or their alloy aerogel and/or foam andmay be used to function both as matrix and as current collector of theanode.

It is emphasized that either or both anode(s) 100A and cathode(s) 100Bmay be prepared with metallic aerogel in which the respective activematerial particles are embedded, e.g., in liquid precursor solutionwhich is dried to from the aerogel with the embedded active materialparticles. Batteries may be assembled from disclosed aerogel-basedanode(s), disclosed aerogel-based cathode(s), or both, possibly inmono-cell configuration. In both aerogel-based anode(s) 100A andaerogel-based cathode(s) 100B, disclosed electrodes improve the energydensity and the conductivity of the electrodes, have spatially uniformresistance, and may not require current collectors, thereby furtherincreasing the battery's energy content and simplifying production.

In certain embodiments, electrode 100 may comprise a cathode of alithium ion cell (e.g., a fast-charging lithium ion cell) and activematerial particles 120 may be cathode active material particles, forexample NCA-based formulations (lithium nickel cobalt aluminum oxide,based on LiNiCoAlO₂) and/or NMC-based formulations (lithium nickelcobalt manganese oxide, based on LiNiCoMnO₂) particles. In someembodiments, cathode active material may comprise any of LMO-basedformulations (lithium manganese oxide, based on LiMn₂O₄), LNM-basedformulations (lithium nickel manganese spinel, based onLiNi_(0.5)Mn_(1.5)O₄), LCO-based formulations (lithium cobalt oxide,based on LiCoO₂), LFP-based formulations (based on LiFePO₄), lithiumrich cathodes and/or combinations thereof. Specific formulations maycomprise mixtures and modifications of any of the cathode materialslisted above. In certain embodiments, cathode active material particles120 may comprise single grains (primary particles) of cathode material,e.g., nanoparticles at the scale of ten to several hundreds ofnanometers in diameter, instead of prior art cathode material particles80 which are conglomerates (secondary particles) of cathode material(primary) nanoparticles 81 and are at the scale of few (e.g., one) toseveral hundreds of micrometers in diameter. In certain embodiments,cathode material grains may be grouped in groups smaller than ten grainsper particle. The inventors have found out that using metallic porousstructure 110 as the supportive structure for cathode active materialnanoparticles 120 enables use of single or few cathode materialnanoparticles as cathode active material nanoparticles 120 rather thanprior art use of conglomerates 80 that include many hundreds ofnanoparticles 120, as illustrated schematically in a non-limiting mannerin FIGS. 2A, 2B for aerogel 110 and foam 110, respectively—by use 104 ofnanoparticles 120 in the cathode, according to some embodiments of theinvention, rather than conglomerates 80 of primary nanoparticles 81 asin the prior art. While in the prior art, secondary (conglomerate)cathode material particles are required to increase the mechanicalstability of the cathode, disclosed embodiments provide enhancedmechanical stability through the use of metallic porous structure 110and therefore allow using smaller particles for the active material.Advantageously, disclosed embodiments provide cathodes with greatlyincreased ratio of surface area to volume of cathode material(nano)particles 120 in comparison to prior art cathode materialparticles 80. In case of cathodes, metallic porous structure 110 maycomprise aluminum, nickel and/or stainless-steel their combinationsand/or their alloy aerogel and/or foam.

In certain embodiments, active material particles 120 may be bound tometallic porous structure 110 to enhance the stability and operabilityof the electrode. For example, cathode active material particles 120 maybe bound to metallic porous structure 110 to enhance the cathodestability (as cathode active material particles typically exhibit lessor not elongation compared to anode active material particles, in whichelongation may be utilized to anchor them in metallic porous structure110).

In certain embodiments, active material particles 120 may be mixed intometallic porous structure 110 either by mixing a slurry thereof with aliquid precursor of metallic porous structure 110 such as aerogel soland/or gel before drying, and/or foam before drying; and/or by insertingactive material particles 120 into prepared (e.g., dried) metallicporous (three dimensional) structure 110, e.g., into pores of theaerogel/foam 110.

It is noted that disclosed aerogels may be formed by a range oftechnologies, with the additional stage of mixing the slurry of activematerial particles 120 into precursor materials for the aerogel, e.g.,in any of the following options: (i) aerogel in the narrow sense,obtained be replacing the liquid phase of a gel (which may be analcohol-based gel or a water-based gel) by a gas while retaining itssolid network with only a slight or no shrinkage in the gel (e.g., undersupercritical conditions or under ambient drying conditions); (ii)xerogel, obtained by removing the liquid phase of a gel (alcohol-basedgel or water-based gel) by evaporation, while retaining its originalshape, possibly with little or no cracks; (iii) cryogel, obtained byfreeze-drying a sol, converting the solvent directly from the solidphase to the gas phase, typically by reducing the pressure around thematerial and adding large amounts of heat; and (iv) hydrogel, comprisinga network of polymer chains that are water-insoluble, e.g., as acolloidal gel with water as the dispersion medium, formingsuperabsorbent natural or synthetic polymers with over 99% water, thatare commonly flexible.

Advantageously, liquid mixture may be made uniform more easily than dryinsertion, while direct insertion is less sensitive to the particle sizedistribution than the liquid method. Certain embodiments combine liquidand dry introduction of active material particles 120 into metallicporous structure 110, possibly with respect to particle sizedistribution parameters. Certain embodiments comprise conductingreactions on active material particles 120 after embedding them inmetallic porous structure 110, e.g., binding reactions between activematerial particles 120 and metallic porous structure 110, and/ormodification or synthesis of active material particles 120 such asreduction (de-oxidation) or alloying (in case metallic porous structure110 withstands the required temperatures. In certain embodiments,reactions of active material particles 120 may be carried out during thedrying of metallic porous structure 110.

In any of the disclosed embodiments, electrodes 100 may comprisemetallic porous structure(s) 110 such as aerogel and/or foam 110 as fullor at least partial replacement of binder(s) and/or additive material(s)that are used in the matrix of prior art electrodes (see FIGS. 3A and3B). Advantageously, electric conductivity of metallic porousstructure(s) 110 such as aerogel and/or foam 110 may allow not using, orusing less conductive additives, and the structure of aerogel and/orfoam 110 may allow not using, or using less binder material. Moreover,ionic conductivity is enhanced by using aerogel and/or foam 110 due toincrease in particle surface area which is available for receiving andproviding lithium ions. Advantageously, using metallic porousstructure(s) 110 such as aerogel and/or foam 110 to support activematerials particles 120 may enhance the mechanical stability ofelectrode, resulting in extended cycle life of the lithium ion cell.Moreover, as at least some of the binder material and conductiveadditives (e.g., carbon, carbon nanotubes) may be removed, the energydensity of electrode 100 may be increased, e.g., by increasing theproportion of active material with respect to prior art. For example,typical prior art electrodes include 2-15 wt %, or possibly 0-40 wt % ofbinders such as PAA (polyacrylic acid), CMC (carboxymethyl cellulose)and/or PVDF (polyvinylidene difluoride). typical prior art electrodesinclude 0-15 wt % conductive additives, e.g., at weight ratios of 5:7:88or 5:0:95 of binder:conductive additives:NCA for NCA-based cathodes.Typical prior art anodes include up to 40 wt % conductive additives,e.g., at weight ratios of 70:15:15 or 33:33:33 ofsilicon:binder:conductive additives for Si anodes. Finally, additionaladvantages comprise a significant reduction in the resistance ofelectrode 100 due to the overall increase in electric conductivity viametallic porous structure 110 and ionic conductivity over the largerexposed surface area. The lower electrode resistance leads in turn tobetter overall performance that may include higher C-rate capabilities,lower operation temperatures, slower degradation rates, etc., withrespect to the prior art.

In certain embodiments, disclosed electrode configurations, withmetallic porous structure 110 supporting active material particles 120,may be implemented in a range of battery technologies other than lithiumion cells, such as Na-ion or Li—S battery or supercapacitors systems, aswell as to anodes comprising any of: carbon-based materials and/orelements of any of IA (Li), IIA (Mg), IIIA (Al, Ga, In), IVA (Si, Ge,Sn, Pb), VA (P, As, Sb, Bi), IB (Ag, Au), and IIB (Zn, Cd) groups of theperiodic table—which have been used in Li-ion, Na-ion and/or Li—Sbattery or supercapacitor systems.

FIGS. 3A and 3B are high-level schematic illustration of prior artelectrodes 90 with active material particles 80 embedded in bindermaterial 95. FIG. 3A illustrates schematically preferred elongation ofanode active material along pores as ionic conductivity paths 92 andFIG. 3B illustrates more realistic particle density which blockelongation in other directions, leading to strongly anisotropic particleelongation with the isotropic binder material 95. Both figuresillustrate schematically the gradual elongation of anode active materialparticles 80 along a few spatial directions 94 as a result of repeatedlithiation and de-lithiation through pores as ionic conductive paths 92.

In the prior art, active material particles 80 are embedded inessentially isotropic matrix 95 that comprises binder material andconductive additives to form electrodes 90 (only a small section thereofis illustrated), be it anode active material particles used to formanodes or cathode active material particles used to form cathodes.Matrix 95 is essentially isotropic and requires formation and/ormaintenance of ionic conductivity through matrix 95 to active materialparticles 80. Typically, pores that serve as ionic conductivity paths 92are formed, which contact active material particles 80 over relativelysmall portions 91 of the surface area of active material particles 80.During operation (and possibly during formation) 82 of the electrode, asthe battery is repeatedly charged and discharged, active materialparticles 80 are repeatedly lithiated and delithiated (indicatedschematically as Li⁺ ions entering and exiting particles 80 throughpores as ionic conductivity paths), causing, in case of anodes offast-charging batteries, gradual elongation 93 of anode active materialparticles 80 in few spatial directions (denoted 94) that correspond totheir contact regions 91 with pores as ionic conductive paths 92—becausethe lithium ions accumulate and cause elongation primarily via contactregions 91 through which they enter and exit anode material particles80. Consequently, anode active material particles 80 become veryelongated (93) along a few directions 94, causing structural andelectrochemical instability of the electrode, raising safety issues andreducing the cycling lifetime of the cell. It is noted that expansion ofthe anode material may also occur along directions 96 other than poresas ionic conductivity paths 92, however at lower rates and at a smallerextension, as neighboring particles 80 typically block mechanicallyfurther expansion (in FIG. 3B particles 80 are illustrated in theirtypically more crowded distribution within matrix 95). Moreover, aspores and ionic conductive paths 92 are typically few and their contactregions 91 are small, material elongation 93 is typically highlyunbalanced over the surface area of particles 80, leading to furthermechanical instability of the anode. While such elongation typicallydoes not occur in cathodes due to the different material structure.Moreover, as illustrated above, active material particles cathodes offast-charging cells are typically used as conglomerates of smallernanoparticles, which in the cases disclosed above—may be modified (seeFIGS. 2A, 2B).

FIG. 4 is a high-level schematic block diagram of a system for anodepreparation and for preparing mono-cell batteries, according to someembodiments of the invention. FIGS. 5A and 5B are schematic high-levelillustrations of raw anode 230 in schematic cross-section and dryetching treatment application 320 (for example, different types of RIE,plasma etchers, ion enhanced etchers) that yields prepared anode 240,respectively, according to some embodiments of the invention. FIGS.5C-5F are schematic high-level illustrations of raw anode 230 inschematic cross-section and dry etching (for example, RIE) treatmentapplication 320 that yields prepared anode 240, respectively, accordingto some embodiments of the invention. It is noted that dry etchingtreatment 320 may comprise in various embodiments any of: differenttypes of RIE—reactive-ion etching, such as induced coupled plasma (ICP),deep RIE (DRIE), planar etch (PE), transformer coupled plasma (TCP),electron cyclotron resonance (ECR) as well as various plasma etchers andion enhanced etchers.

System 200 comprises an anode preparation unit 210 configured to preparea raw anode 230 from oxidized active material particles 232 (e.g.,comprising active material 233A at least partly covered by an oxidelayer 233B) and a supporting structure 234 that includes electronconductive elements 236 and pores that serve as ion conductive paths 235that interconnect oxidized active material particles 230 amongthemselves and to a surface 230A of raw anode 230.

System 200 and/or anode preparation unit 210 further comprises a dryetching unit 220 (for example, different types of RIE, plasma etchers,ion enhanced etchers) configured to apply a dry etching treatment 320 toraw anode 230, to at least partly reduce oxidized active materialparticles 232 through pores and paths 235 (indicated schematically bynumeral 322) and yield a prepared anode 240, ready for assembly and usein a battery.

In certain embodiments, anode preparation unit 210 may be configured toembed oxidized active material particles 232 in electrically conductivemetallic porous structure 110 as porous supporting structure 234. Incertain embodiments, the amount of binder(s) and/or additive(s) may bereduced or even binder(s) and/or additive(s) may be removed completely,e.g., to yield binder-free prepared anodes 240 (possibly alsobinder-free raw anodes 230), e.g., as electrically conductive metallicporous structure 110 may provide sufficient cohesivity to the electrode.

In certain embodiments, anode preparation unit 210 may be configured toprepare raw anode 230 in an aqueous (water-based) environment, such asin a water-based slurry, or in any other potentially oxidizingenvironment, such as air. Advantageously, as active material particles232 in raw anode 230 are oxidized (and are at least partly de-oxidized,or reduced, during dry etching treatment 320), preparation processes maybe simplified significantly, and have enhanced productivity and safety,as oxidized active material particles 232 are much less reactive thanprior art non-oxidized active material particles.

Dry etching treatment 320 (e.g., different types of RIE, plasma etchers,ion enhanced etchers) may be performed as dry etching under lowpressure, applying high-energy ions from the plasma to attack surfaceregions of oxidized active material particles 230 and de-oxidize(reduce) them. Various inert and reactive chemistries may be used fordry etching treatment 320, e.g., fluorocarbons, oxygen, chlorine, borontrichloride with or without addition of nitrogen, argon, helium,methane, hydrogen and/or other gases.

In certain embodiments, dry etching treatment 320 may be configured toenhance the porosity and/or modify the structure of the treatedelectrode(s), e.g., to further enhance any of the electrode's ionconductivity, the electrode's interface with the electrolyte andwettability thereby, the electrode's mechanical stability etc.

In various embodiments, system 200 may further comprise apost-processing unit 250 configured to stabilize the anode mechanicallyand/or passivate the anode chemically after the dry etching treatment,and/or to apply a post-treatment at least to surface 240A of preparedanode 240. For example, any of temperature treatment, pressureapplication, light irradiation and/or solvent exposure, may be used topost-treat anode 240, to stabilize the anode structure and/or to enhanceelectron and/or ion conductivity thereof. In certain embodiments,reactions between anode material particles 232 and porous structure 234may be initiated to further stabilize anode 240. In certain embodiments,reactions may occur not only between active material particles and theporous structure, but also with the binder and conductive additives,e.g., under certain environmental conditions such as specific values ofpressure, temperature, light, certain solvents, etc. In certainembodiments, the amounts of binder(s) and/or conductive additive(s) maybe increased during the preparation of raw anode 230, to compensate forremoval thereof during dry etching treatment 320 and enhance thestability of prepared anode 240.

In certain embodiments, dry etching treatment 320 may be applied toelectrodes 100 made of active material particles 120 embedded inelectrically conductive metallic porous structure 110, such as aerogeland/or foam 110, as exemplified below. In certain embodiments, disclosedelectrodes may have a reduced amount of binders and/or additives, andpossibly even no binders and/or additives, and may comprise solelyactive material particles 232 and porous structure 234. Moreover,electrically conductive metallic porous structure 110 may at leastpartly, or fully, replace the current collector, to make the electroderesistance more uniform and spare additional material and volume.

As illustrated schematically in FIG. 5A, anode preparation unit 210 isconfigured to yield raw anode 230 with porous structure 234 having pores235A and ion conductive paths 235 that interconnect particles 232 amongthemselves and to surface 230A—by mixing respective materials, e.g., ina slurry that can be water-based, to assure the requiredinterconnections. Electron conductive elements 236 may comprise carbonin any of its forms, e.g., carbon, carbon fibers, carbon nanotubes etc.,as e.g., taught by U.S. patent application Ser. No. 15/414,655,incorporated herein by reference in its entirety, and may likewise byapplied in the anode preparation process in a way that interconnectsparticles 230 among themselves and to surface 230A.

FIG. 5B schematically illustrates the utilization of pores 235A and/orpaths 235 that contact, at contact regions 242, oxidized active materialparticles 232 embedded in porous structure 234—to introduce dry etchingmaterial 222 (e.g., plasma or other ionized material, such as indifferent types of RIE, plasma etchers, ion enhanced etchers) thatpenetrates through pores 235A and/or paths 235, to reduce (de-oxidize)at least contact regions 242 on particles 232 (indicated schematicallyby arrows 322), and to establish the ionic conductivity of porousstructure 235 with respect to treated particles 232—by removing at leastsome of oxide layer 233B from contact regions 242. It is noted that incase some of oxide layer 233B remains on particles 232, it does notreduce the ion conductivity of particles 232 and of anode 240, as suchremains are anyhow not available to Li ions due to low ionicconductivity at their location. It is further noted, that remainingparts of oxide layer 233B also do not impede electron conductivity,e.g., as metalloid oxides, especially with low thickness, are typicallyelectron-conductive. Therefore, both electron and ion conductivity fromanode surface 240A to active material particles 232 are provided bydisclosed methods and systems. It is noted that disclosed anodes 240 maybe used with any of liquid, solid and/or semi-solid (e.g., polymerand/or gel) electrolytes, as well as combinations thereof, through whichlithium ions reach anode surface 240A and active material particles 232,e.g., at least along same pores 235A and/or ion conductive paths 235through which dry plasma treatment 222 (indicated schematically by arrow322), and possibly through additional pores that may have been madeavailable by the dry etch treatment.

In various embodiments, dry etching treatment 320 (e.g., different typesof RIE, plasma etchers, ion enhanced etchers) may be applied toelectrodes 100 made of active material particles 120 embedded inelectrically conductive metallic porous structure 110, such as aerogeland/or foam 110 (see also FIG. 4 ). Such combinations simplify theproduction of electrodes 100 as active material particles 120 can beprocessed and embedded in electrically conductive metallic porousstructure 110 without avoiding their surface oxidation, while dryetching treatment 320 may be made simpler by highly porous structure110.

For example, as illustrated schematically in FIGS. 5C, 5E and 5D, 5Fanode preparation unit 210 may configured to yield raw anode 230 (FIGS.5C, 5E) with metallic porous structure 110 that provides ion conductivepaths 235 that interconnect particles 120 among themselves and to thesurface of metallic porous structure 110. The highly porous structure ofmetallic porous structure 110, e.g., as aerogel (FIGS. 5C, 5D) and/orfoam (FIGS. 5E, 5F), ensures extensive access of dry etching treatment320 (e.g., plasma or other ionic material 222, such as comprising inertand reactive chemistries such as any of argon, helium, methane,hydrogen, nitrogen, oxygen, chlorine, boron trichloride, fluorocarbonsor combinations thereof) to oxide surface 233B of active materialparticles 120. Application of dry etching 320 (FIGS. 5D, 5F) utilizespores and paths 235 in metallic porous structure 110 to reduce at leastparts of oxidized surface 233B (indicated schematically by arrows 322)to yield multiple ion conductive regions 242 on the surface of activematerial particles 120 providing access for lithium ions of theparticle's internal active material 233A. The high porosity of metallicporous structure 110 ensures efficient reduction of oxide layer 233B andconsequently high efficiency of lithiation and de-lithiation of activematerial particles 120 and electrodes 100. In certain embodiments,disclosed electrodes may be binder-free, being composed only of metallicporous structure 110 and active material particles 120. Resultingprepared electrodes 100 such as prepared anodes 240 are highly efficientin fast-charging lithium cells, and maintain structural stability andelectric conductivity due to metallic porous structure 110, as explainedabove.

Referring back to FIG. 4 , certain embodiments comprise batterypreparation systems 265 which comprise anode preparation unit 210configured to prepare raw anode(s) 230 from oxidized anode activematerial particles 232 and porous supporting structure 234 that includeselectron conductive elements and pores that interconnect the oxidizedanode active material particles among themselves and to a surface of rawanode(s) 230, and/or by embedding oxidized anode active materialparticles 232 in electrically conductive metallic porous structure 110to yield raw anode(s) 230; dry etching unit 220 configured to apply dryetching treatment 320 to raw anode(s) 230 prepared in either method, toat least partly reduce the oxidized anode active material particlesthrough the pores and yield anode(s) 240 and/or 100 in operable state;and an assembly unit 260 configured to assemble a mono-cell battery 270from one (or more) anode(s) 240 and/or 100A and one (or more) cathode(s)100B which have a spatially uniform resistance, e.g., prepared byembedding primary cathode active material particles in correspondingelectrically conductive metallic porous structure 110. It is noted thatFIG. 4 illustrates schematically multiple alternative and/or optionalcomponents of systems 265 and electrodes 100 which may be combined invarious ways to yield disclosed embodiments.

In non-limiting examples, the anode active material particles maycomprise particles of any of metalloids comprising Si, Ge and/or Sn,metals comprising Mn and/or Fe particles, and/or carbon-based materialcomprising graphite and/or graphene and the anode electricallyconductive metallic porous structure may comprise aerogel and/or foamthat comprise copper, nickel and/or titanium, their combinations and/ortheir alloys.

In certain embodiments, systems 265 may comprise a cathode preparationunit 275 configured to embed primary cathode active material particles120, which may be single grains or be at groups smaller than 10, inelectrically conductive metallic porous structure 110 to yieldcathode(s) 100B. In non-limiting examples, the cathode electricallyconductive metallic porous structure may comprise aerogel/foamcomprising any of aluminum, nickel and/or stainless-steel, theircombinations and/or their alloys.

In certain embodiments, systems 265 may be configured to assemblemono-cell battery 270 from one anode 100A and one cathode 100B,separated by a semi-solid separator 134. Advantageously, for anode(s)100A and cathode(s) 100B which have a spatially uniform resistance,electrodes 100 may be made to be thick, simplifying assembly and sparingspace by not requiring folding and elaborate separators, whilemaintaining low resistance and good conductivity due to the structureand construction of electrodes 100, as disclosed herein. Moreover,mono-cell batteries 270 may have low resistance, uniform cell parametersand higher energy density. Current collection may be carried out by therespective electrically conductive metallic porous structures 110 ofanode(s) 100A and cathode(s) 100B, respectively, further simplifyingassembly, sparing additional space and maintaining the spatially uniformresistance of electrodes 100.

In certain embodiments, anode(s) and/or cathode(s) of disclosedmono-cell battery 270 may be binder-free and/or may be configured tohave a specified form factor, such especially broad, or having aspecified shape which is unattainable by prior art batteries that arelimited in their form factor by the larger number of components and morecomplex assembly process. In certain embodiments, anode(s) and/orcathode(s) of disclosed mono-cell battery 270 may be between 200 μm and1 mm thick.

FIGS. 6A and 6B are high-level illustrations of batteries 130, accordingto some embodiments of the invention. In FIG. 6A, Battery 130 isillustrated in views that show anode “A” 100A/80 (with corresponding tab132A), separator “S” 134 and cathode “C” 100B/80 (with corresponding tab132B) in electrolyte “E” 133 within pouch 131 at face view and sideviews in a very schematic manner. It is noted that disclosed embodimentsare applicable to various cell configurations such as soft pouch(package) cells, cylindrical cells, coin or button cells, prismaticcells, etc. Clearly, multiple anodes, cathodes and/or separators mayconstitute the battery, the exact structure of which is not shown. Asindicated, disclosed electrodes 100 may be integrated in the battery (orcell) in various configurations, e.g., as anode 100A, cathode 100B, withboth anodes 100A and cathodes 100B used in the battery or with just onetype of anode(s) 100A or cathode(s) 100B used with corresponding priorart cathode(s) or anode(s) 80, respectively or in combinations thereofin different cells of the battery. Electrodes 100, namely either or bothanode(s) 100A and/or cathode(s) 100B may comprise current collectors135A, 135B, respectively as do prior art electrodes 80, or anode(s) 100Aand/or cathode(s) 100B may be used without corresponding currentcollectors, using portion(s) of aerogel and/or foam 110 as therespective current collector replacement—as indicated schematically inthe right-hand illustration in FIG. 6A.

FIG. 6B illustrates schematically electrode 100 that may replace priorart electrodes 80, according to some embodiments of the invention. Priorart electrodes 80 typically comprise two electrodes 80 that areattached, back-to-back, to a current collector 135, e.g., currentcollectors 135A, 135B for prior art anodes and cathodes, respectively,denoted schematically as 80 (A/C). Lithium ions Li+ are indicatedschematically as entering and exiting electrodes 80 on either side ofcurrent collector 135, with respect to complementary electrodes that arenot shown. Disclosed electrodes 100 (anodes 100A and/or cathodes 100B)may replace (indicated by arrow 106) either or both prior art anodesand/or cathodes 80 (A/C), respectively, optionally disposing of priorart intermediate current collector 135 as metallic porous structure 110functions to replace it.

Due to prior art electrode structure, the active material particles inprior art electrodes 80 experience different resistance values due tohaving varying levels of proximity to current collector 135, varyingelectron conductivity paths to current collector 135, varying ionconductivity paths to the electrolyte, and varying amounts and geometricorganization of binders (and additives) surrounding the active materialparticles. The prior art different resistance values result in overallhigh prior art electrode resistance and non-uniform activity anddegradation of the prior art active material particles. In contrast, andadvantageously, active material particles in disclosed electrodes 100experience much more uniform conditions and resistance values, becausemetallic porous structure 110 surrounds the particles and provides moreuniform electron conductivity, the multitude of pores in porousstructure 110 provide a high and more uniform degree of ion conductivityand less or no binder is present. Consequently, disclosed electrodes 100have lower overall resistance than prior art electrodes 80 and activematerial particles 120 experience more uniform conditions and thereforedegrade more uniformly—extending the overall cycling lifetime ofelectrodes 100. Moreover, disclosed electrodes 100 enable producingthinner cells than in the prior art, as current collectors 135 are notnecessarily required and/or producing electrodes 100 with higher energydensity, as the higher and more uniform electron and ion conductivityand the higher porosity enable increasing the density of active materialparticles 120 within electrodes 100. Certain embodiments comprise cells130 configured as mono-cells, having one anode 100A and one cathode 100Bseparated by separator 134 and/or semi-solid electrolyte 133—simplifyingthe assembly processes (e.g., stacking, winding and/or folding) andfurther increasing the energy density, e.g., by estimated 1-15% (orintermediate values), depending of the type of battery and volume ofseparator used in the prior art, as no multiple current collectors 135and fewer separators 134 are required. For example, in prior arthigh-energy cells, high load electrodes are used with thicker electrodesand less separator, occupying only ca. 1% of the cell thickness. Inanother example, in prior art high-power cells, thinner electrodes areused and the separator occupies a larger portion of the cell thicknesssince more electrodes are used, e.g., up to 15%. Disclosed cellconfigurations may be used to reduce most of the separator volume ineither application. In various embodiments, cells 130 may be designed tohave specified resistance and capacity values, by modifying theelectrode thickness and the active material density, while keepingsimilar electrode structure and uniform resistance and degradationvalues.

FIGS. 7A and 7B are high-level schematic illustrations of mono-cellbatteries 130, according to some embodiments of the invention, comparedwith prior art battery configurations illustrated schematically in FIGS.7C and 7D.

Prior art batteries 60 comprise folded stacks 70 of multiple alternatingsheets of anodes (with respective current collector) 80A, separators 134and cathodes (with respective current collector) 80B—making batteryassembly processes complex, requiring any of 1%, 5%, 10%, 15% or anyintermediate value as additional cell volume for separators, and makethe batteries sensitive to inconsistencies in layer thickness (due toproduction and/or operation) which may result in safety issues. Priorart assembly processes are complex, requiring intricate folding orrolling procedure to reach the fine lamellar structure of prior artbatteries 60. Moreover, electrolyte filling is more complicated as goodcontact must be established between the electrolyte and all electrodes,possibly requiring additional operations such as vacuum and/or pressureapplication 65.

As shown above, disclosed electrode 100 configurations overcome theprior art varying resistance of different active material particles thatdepends on their location and distance from the current collectors, andyield electrodes 100 with spatially uniform resistance. Therefore,disclosed electrode configurations are less or not sensitive toelectrode thickness, avoiding the dependency of electrode resistance onelectrode thickness which is so prominent in the prior art. Moreover,disclosed electrodes and batteries may have more variable form factorsthan in the prior art due to the simpler assembly, smaller number ofcomponents and simpler spatial structure. For example, not only theirthickness but also the lateral dimensions of the electrodes andbatteries may be more freely adjusted to the application, e.g., beconfigured to have larger lateral dimensions (e.g., broader and flatter,or have specified shapes which are not attainable with prior arttechnology) for different applications such as consumer, EV, grid, etc.Especially using metallic porous structure 110 as the current collectorprovides highly effective and stable transportation of electrons.

Certain embodiments comprise using fewer and thicker layers of anode100A and cathodes 100B, and consequently smaller volume of separator134, simpler assembly process, and simpler preparation for operation.Certain embodiments, illustrated schematically in FIGS. 7A and 7B, evenenable producing batteries 270 as mono-cells—with single anode 100A andsingle cathode 100B separated by separator 134, and produced in a muchsimpler assembly process (see e.g., FIG. 4 ). In various embodiments,anode 100A and cathode 100B may be much thicker than prior art anode 80Aand cathode 80B, respectively, as electrode active material particlesexperience the same resistance irrespective of their location within theelectrode, as explained above. For example, while prior art anodes areabout 10-150 μm on each side of the anode current collector that isabout 5-15 μm thick and prior art cathodes are about 20-300 μm on eachside of the cathode current collector that is about 5-15 μm thick, andprior art separator thickness is about 6-15 μm, disclosed cells maycomprise single anodes having a thickness of 50 μm to 5 mm and singlecathodes having a thickness of 50 μm to 5 mm, with a single intermediateseparator (rather than prior art multiple, folded separator sheets). Incertain embodiments, anodes 100A and cathodes 100B may be configuredwith respective active material particles 120 embedded in metallicporous structure 110, and possibly treated with dry etching 320.

Certain embodiments comprise mono-cell batteries 270 comprising at leastone (or single) anode 100A and at least one (or single) cathode 100Bseparated by at least one (or single) separator 134 or by semi-solidelectrolyte 134, wherein anode 100A and cathode 100B comprisecorresponding anode and cathode active material particles 120 embeddedin respective electrically conductive metallic porous structures 110,e.g., foams illustrated schematically in FIG. 7A, aerogels illustratedschematically in FIG. 7B, or combinations thereof, e.g., different anode100A and cathode 100B. For example, anode active material particles 120may comprise particles of metalloids comprising Si, Ge and/or Sn, metalscomprising Mn and/or Fe particles, and/or carbon-based materialcomprising graphite and/or graphene, and anode electrically conductivemetallic porous structure 110 may comprise aerogel and/or foam thatcomprise any of copper, nickel and/or titanium, their combinationsand/or their alloys. For example, cathode active material particles 120may comprise primary cathode material nanoparticles which are singlegrains or are at groups smaller than 10, and cathode electricallyconductive metallic porous structure 110 may comprise aerogel and/orfoam made of any of aluminum, nickel and/or stainless-steel theircombinations and/or their alloys. In certain embodiments, anode(s) 100Aand/or cathode(s) 100B may be prepared by dry etching 320 to remove atleast part of an oxidized surface of the respective active materialparticles, thereby simplifying the production process and furtherutilizing the porous structure of electrically conductive metallicporous structures 110 such as aerogels or foams. Mono-cell batteries 270may be configured as any of Li-ion, Na-ion and/or Li—S battery orsupercapacitors.

Anode(s) and/or cathode(s) of disclosed batteries may have specifieddimensions and/or form factors, and may be produced by any cellmanufacturing technology, such as prismatic cell configurations, coin orbutton cells, cylindrical cell configurations and soft pouch cellconfigurations. Any corresponding electrode size may be produced, e.g.,ranging from 1 mm to 1 m or even longer in any of its dimensions, e.g.,1 mm, 10 cm, tens of cm, 1 m, etc., as well as intermediate values, andany electrode thickness may be used, due to the spatially-uniformresistance, e.g., ranging from 0.1 mm through 1 mm, 1 cm to 10 cm, aswell as intermediate values, depending on the relation between anode andcathode load and the desired cathode/anode ratio. For example, a fewnon-limiting designs for cylindrical cells are presented below.

FIGS. 8B-8E are high-level schematic illustrations of cylindrical celldesigns according to some embodiments of the invention, compared withprior art cylindrical cell design illustrated in FIG. 8A. As illustratedin FIG. 8A, cylindrical prior art batteries 60 typically have anodes 80Aand cathodes 80B that are rolled with separator 134 within a case 55—toform a multi-layered cylinder, and typically have a central pin (orhollow) 40 related to the wound structure. Anodes 80A and cathodes 80Bhave respective bottom and top current collectors 50A, 50B connectedthereto and to the battery's external contacts, of which only cap 45,connected to cathodic current collector 50B, is shown in theillustration. Specifically, cathodic current collector 50B typically hasa structure pressing it against cap 45, to accommodate sealing plate 47with insulating gasket 43, insulating ring 48 and vent 46 at the top ofbattery 60. Current collectors 50A, 50B are connected to the bottom andtop of case 55, respectively, as external contacts.

FIGS. 8B-8E illustrate various embodiments of configuring mono-cellbattery 270, having one anode 100A and one cathode 100B, separated byseparator 134, into the cylindrical cell structure, in ways that improvethe energy content of the battery and simplify its structure andproduction. In the configuration illustrated in FIG. 8B, case 55, pin 40and cap structures 45, 47, 43, 48, 46 are retained as in the prior art,as are the basic structures of the contacts 50A, 50B, with minimaladjustments (not shown), and with or without tabs that are welded to theelectrodes (see, e.g., schematic FIG. 6A). Using single anode 100A andsingle cathode 100B provides higher energy density (as no space is lostto additional separator and windings) and simpler structure thatsimplifies assembly of mono-cell 270 with respect to prior art cell 60.FIG. 8C illustrates a tab-less structure, with contacts 105A, 105B(e.g., electrical connections) of anode 100A and cathode 100B,respectively, in direct contact with the bottom and top externalcontacts of cell 270. FIGS. 8B and 8C illustrate a generallylongitudinal arrangement of anode 100A and cathode 100B (parallel to thecell axis), following prior art longitudinal arrangement of rolledanodes 80A and cathodes 80B, which was designed to conform with thecell's longitudinal structure. It is noted that the metallic aerogeland/or porous structure provides electric conductivity throughout eachof anode 100A and cathode 100B, making prior art winding based structureunnecessary and reducing amount of separators 134, gaining additionalenergy content for the space they have taken. It is further noted thatsingle anode 100A and single cathode 100B have spatially-uniformresistance, which enables efficient operation of the active material,irrespective of its distant from respective contacts 105A, 105B.

In contrast, FIGS. 8D and 8E provide mono-cell configurations 270, inwhich single anode 100A and single cathode 100B are positionedtransversely in cell 270 (parallel to the cell axis) further simplifyingcell structure and assembly and further increasing its energy capacity,compared to prior art cells 60. In FIGS. 8D and 8E, the contacts fromanode 100A and cathode 100B are provided to the respective bottom partof case 55 and cap 45, respectively (illustrated in FIG. 8E), withinsulator 136 (shown schematically) electrically insulating bottom case55 from cap 45. Contacts 105A, 105B (without the need for prior artcurrent collectors) may be connected to the bottom and top of case 55,respectively, which function as external contacts. In FIGS. 8D and 8E,the central space (occupied in the prior art by pin 40 or a hollow) isoccupied by anode 100A and cathode 100B, increasing the energy contentof cell 270 and further simplifying assembly. It is noted that inembodiments with longitudinal anode 100A and cathode 100B, similar tothose illustrated in FIG. 8B, 8C, may also be modified to occupy thecentral space (corresponding to pin 40 in prior art batteries 60), e.g.,by cathode 100B.

FIG. 9 is a high-level flowchart illustrating methods 300, according tosome embodiments of the invention. The method stages may be carried outwith respect to system 200 described above, which may optionally beconfigured to implement method 300. Method 300 may comprise thefollowing stages, irrespective of their order.

Method 300 comprises preparing an anode for a lithium ion battery, bypreparing a raw anode (stage 310) from oxidized active materialparticles and a porous supporting structure that includes electronconductive elements and pores that interconnect the oxidized activematerial particles among themselves and to a surface of the raw anode,and applying a dry etching treatment (e.g., different types of RIE suchas ICP, DRIE, PE, TCP, ECR, as well as various plasma etchers and ionenhanced etchers) (stage 320) to the raw anode to at least partly reducethe oxidized active material particles through the pores to yield theanode in an operable state. The pores may be configured as ionconductive paths that interconnect the active material particles amongthemselves and/or with a surface of the anode.

In certain embodiments, method 300 may further comprise increasingamounts of binder(s) and/or conductive additive(s) during thepreparation of the raw anode, to compensate for removal thereof duringthe dry etching treatment (stage 315).

In certain embodiments, method 300 may comprise embedding the oxidizedactive material particles in an electrically conductive metallic porousstructure as the porous supporting structure (see stage 360 below). Incertain embodiments, method 300 may comprise reducing the amounts oraltogether eliminating binder(s) and/or additive(s), and possibly thecurrent collector as well, e.g., when using the electrically conductivemetallic porous structure as the porous supporting structure (stage340).

In certain embodiments, method 300 may comprise carrying out preparing310 in an aqueous (water-based) environment, such as in a water-basedslurry, or in any other potentially oxidizing environment, such as air(stage 345).

In certain embodiments, method 300 may further comprise any ofstabilizing the anode mechanically after the dry etching treatment(stage 330), passivating the anode chemically after the dry etchingtreatment (stage 332), and/or applying a post-treatment at least to thesurface of the anode (stage 334), to stabilize the anode structureand/or to enhance electron and/or ion conductivity thereof.

Advantageously, disclosed systems 100 and methods 300 overcome a centraldifficulty in the preparation of anodes (e.g., for lithium ionbatteries, e.g., metalloid-based anodes for fast charging lithium ionbatteries), namely the need to keep the active material activethroughout the anode preparation process—which requires carefulpreparation procedures to avoid active material oxidation, preparing theanode under inert atmosphere etc. Prior art solvent-based preparationprocesses are also problematic with respect to the reactivity of theactive material particles, as these may react with the respectivesolvents (e.g., water) or by modified inside the solvent (e.g., byagglomeration). Such cases make it hard or even impossible to manage theelectrode preparation process and may result in performance and safetydecreases. Moreover, anode preparation processes are typicallywater-based and are therefore inherently inclined to oxidize the activematerial if it is not fully isolated from the water used in thepreparation process. In contrast, disclosed systems 200 and methods 300enable simple handling and preparation of raw anode 230 from oxidizedactive material particles 232, while providing the required electronicand ionic conductivity by reducing (de-oxidizing) surface areas 242 ofoxidized active material particles 232 which contact porous structure134 in the anode structure. Advantageously, oxidized active materialparticles are much more stable and have lower surface energies thannon-oxidized particles used in the prior art, allowing better and safermanagement of the electrode preparation process. Moreover, disclosed dryetching treatment 320 (e.g., different types of RIE, plasma etchers, ionenhanced etchers) is sufficient to activate raw anode 230 and yieldprepared anode 240 because de-oxidized (reduced) surface areas 242 arethe regions required to be ion-conductive as they contact porousstructure 234—which are also the paths through which plasma treatment320 is applied.

FIG. 9 further illustrates schematically methods 350, according to someembodiments of the invention. The method stages may be carried out toform electrode(s) 100 described above. Method 350 may comprise thefollowing stages, irrespective of their order, which may be combinedwith other stages of methods 300.

Method 350 may comprise embedding active material particles in anelectrically conductive metallic porous structure to yield an electrode(stage 360). For example, the distribution of the embedded activematerial particles in the metallic porous structure may be uniform.

In certain embodiments, embedding 360 may comprise mixing a slurry ofthe active material particles with an aerogel in sol and/or gel form anddrying the sol and/or gel form to yield the metallic porous structurewith the embedded active material particles (stage 370). For example,the mixing may be configured to yield a uniform mixture, and upondrying, a uniform distribution of the embedded active material particlesin the aerogel.

In certain embodiments, embedding 360 may comprise mixing a slurry ofthe active material particles with a foam and drying the foam to yieldthe metallic porous structure with the embedded active materialparticles (stage 380). For example, the mixing may be configured toyield a uniform mixture, and upon drying, a uniform distribution of theembedded active material particles in the dried foam.

In certain embodiments, embedding 360 may comprise introducing theactive material particles directly into the prepared metallic porousstructure (stage 390) and binding the active material particles to themetallic porous structure, to yield the metallic porous structure withthe embedded active material particles (stage 395). For example, theintroduction of the active material particles may be carried out in away that yields a uniform mixture.

FIG. 9 further illustrates schematically methods 400, according to someembodiments of the invention. The method stages may be carried out toform electrode(s) 100 (or 240) described above. Method 400 may comprisethe following stages, irrespective of their order, which may be combinedwith other stages of methods 300 and 350.

Certain embodiments of method 400 comprise implementing stages of method300 such as dry etch treatment 320 on raw anodes prepared according tostages of method 350, e.g., with aerogel and/or foam as metallic porousstructure (stage 410). Certain embodiments utilize the highly porousstructure of aerogel or foam metallic porous structure to reduce most orall of the surface of the oxidized active material particles (stage412), yield high ionic and electric conductivity, and moreover produceelectrodes (anode and/or cathodes) with spatially uniform resistance(stage 414), as conductivity is not determined by a distance to acurrent collector, which in certain embodiments may be replaced bymetallic porous structure itself (stage 416).

In certain embodiments, method 300 may comprise preparing mono-cellbatteries from disclosed electrodes (stage 420).

FIG. 9 further illustrates schematically battery preparation methods420, according to some embodiments of the invention. The method stagesmay be carried out to form mono-cell batteries 270 described above.Method 420 may comprise the following stages, irrespective of theirorder, which may be combined with other stages of methods 300, 350 and400.

In certain embodiments, method 420 comprises preparing the batteries bypreparing at least one anode and at least one cathode which have aspatially uniform resistance (stage 430) and combining the at least oneanode and the at least one cathode into a mono-cell batteryconfiguration (stage 440). For example, preparation 430 may be carriedout by embedding anode and cathode active material particles inrespective electrically conductive metallic porous structures to yieldthe respective at least one anode and at least one cathode (stage 450).

In certain embodiments, the anode active material particles may compriseparticles of at least one of: metalloids comprising Si, Ge and/or Sn,metals comprising Mn and/or Fe particles, and/or carbon-based materialcomprising graphite and/or graphene and the anode electricallyconductive metallic porous structure comprises aerogel and/or foam thatcomprise copper, nickel and/or titanium, their combinations and/or theiralloys. In certain embodiments, the cathode active material particlesmay comprise primary cathode material nanoparticles which are singlegrains or are at groups smaller than 10, and wherein the cathodeelectrically conductive metallic porous structure comprises aerogeland/or foam made of aluminum, nickel and/or stainless-steel theircombinations and/or their alloys.

In certain embodiments, method 420 may further comprise preparing atleast one raw anode from oxidized anode active material particles and aporous supporting structure that includes electron conductive elementsand pores that interconnect the oxidized active material particles amongthemselves and to a surface of the at least one raw anode (stage 460),and applying a dry etching treatment to the at least one raw anode to atleast partly reduce the oxidized anode active material particles throughthe pores and yield the at least one anode in an operable state (stage470).

Method 420 may further comprise configuring a mono-cell battery from oneanode and one cathode separated by a separator or by a semi-solidelectrolyte (stage 480), wherein the anode and the cathode comprise theelectrode, prepared with corresponding anode and cathode active materialparticles.

Disclosed lithium ion batteries may be configured, e.g., by selection ofmaterials, to enable operation at high charging and/or discharging rates(C-rate), ranging from 3-10 C-rate, 10-100 C-rate or even above 100C,e.g., 4C, 5C, 10C, 15C, 30C or more. It is noted that the term C-rate isa measure of charging and/or discharging of cell/battery capacity, e.g.,with 1C denoting charging and/or discharging the cell in an hour, and XC(e.g., 5C, 10C, 50C etc.) denoting charging and/or discharging the cellin 1/X of an hour—with respect to a given capacity of the cell.

Fast charging cells may comprise rechargeable Li-ion cells having anodematerial based on metalloids such as Si, Ge and/or Sn, as taught e.g.,by any of U.S. Pat. Nos. 9,472,804 and 10,096,859, and U.S. patentapplication Ser. Nos. 15/480,888, 15/414,655 and 15/844,689, which areincorporated herein by reference in their entirety. Disclosedembodiments may be applied to metalloid (Si, Ge and/or Sn)-based anodesfor fast charging lithium ion cells.

The active material particles may comprise metalloids such as Si, Geand/or Sn particles, metals such as Mn and/or Fe and/or carbon-basedmaterial such as graphite and/or graphene, and/or combinations thereofas anode material, and the metallic porous structure may compriseaerogel/foam made of any of aluminum, nickel, copper, gold, titanium,stainless steel, their combinations and/or their alloys; and/or theactive material particles may comprise any of NCA-based, NMC-based,LFP-based, LNM-based and/or LMO-based particles as cathode material andthe metallic porous structure may comprise aerogel/foam that comprisealuminum, nickel and/or stainless-steel their combinations and/or theiralloys. In any of these cathode materials, primary particles rather thansecondary particles may be used in disclosed cathodes.

It is noted that in batteries 130, separator(s) 134 may comprise variousmaterials, e.g., polymers such as any of polyethylene (PE),polypropylene (PP), polyethylene terephthalate (PET), poly vinylidenefluoride (PVDF), polymer membranes such as a polyolefin, polypropylene,or polyethylene membranes. Multi-membranes made of these materials,micro-porous films thereof, woven or non-woven fabrics etc. may be usedas separator(s), as well as possibly composite materials including,e.g., alumina, zirconia, titania, magnesia, silica and calcium carbonatealong with various polymer components as listed above.

Electrolytes 133 may comprise linear and cyclic carbonate solvents suchas dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methylcarbonate (EMC) or esters such as ethyl acetate (EA), propionates andbutyrates; and ethylene carbonate (EC), fluoroethylene carbonate (FEC)or vinylene carbonate (VC), respectively. For example, electrolytes maycomprise a large proportion, e.g., 10%, 20%, 30% or more of VC and/orFEC as prominent cyclic carbonate compound, as disclosed e.g., in U.S.patent application Ser. No. 15/844,689, incorporated herein by referencein its entirety.

Electrolytes 133 may comprise solid electrolytes such as polymericelectrolytes such as polyethylene oxide, fluorine-containing polymersand copolymers (e.g., polytetrafluoroethylene), and combinationsthereof.

Electrolytes 133 further comprise lithium electrolyte salt(s) such asLiPF₆, LiBF₄, lithium bis(oxalato)borate, LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂,LiAsF₆, LiC(CF₃SO₂)₃, LiClO₄, LiTFSI, LiB(C₂O₄)₂, LiBF₂(C₂O₄)),tris(trimethylsilyl)phosphite (TMSP), and combinations thereof.

Electrolytes 133 may comprise solid or semi-solid electrolytes, such aspolymeric electrolytes, e.g., polyethylene oxide, fluorine-containingpolymers and copolymers (e.g., polytetrafluoroethylene), flexiblepolymeric and/or gel electrolytes, and/or combinations thereof, e.g., astaught e.g., by WIPO Application No. PCT/IL2017/051358, incorporatedherein by reference in its entirety.

In the above description, an embodiment is an example or implementationof the invention. The various appearances of “one embodiment”, “anembodiment”, “certain embodiments” or “some embodiments” do notnecessarily all refer to the same embodiments. Although various featuresof the invention may be described in the context of a single embodiment,the features may also be provided separately or in any suitablecombination. Conversely, although the invention may be described hereinin the context of separate embodiments for clarity, the invention mayalso be implemented in a single embodiment. Certain embodiments of theinvention may include features from different embodiments disclosedabove, and certain embodiments may incorporate elements from otherembodiments disclosed above. The disclosure of elements of the inventionin the context of a specific embodiment is not to be taken as limitingtheir use in the specific embodiment alone. Furthermore, it is to beunderstood that the invention can be carried out or practiced in variousways and that the invention can be implemented in certain embodimentsother than the ones outlined in the description above.

The invention is not limited to those diagrams or to the correspondingdescriptions. For example, flow need not move through each illustratedbox or state, or in exactly the same order as illustrated and described.Meanings of technical and scientific terms used herein are to becommonly understood as by one of ordinary skill in the art to which theinvention belongs, unless otherwise defined. While the invention hasbeen described with respect to a limited number of embodiments, theseshould not be construed as limitations on the scope of the invention,but rather as exemplifications of some of the preferred embodiments.Other possible variations, modifications, and applications are alsowithin the scope of the invention. Accordingly, the scope of theinvention should not be limited by what has thus far been described, butby the appended claims and their legal equivalents.

What is claimed is:
 1. An electrode comprising active material particlesembedded in an electrically conductive porous structure that comprises(a) an electrically conductive metallic aerogel that comprises ananisotropic assembly of wires or needles, and (b) open-cell foamscomprising an anisotropic assembly of cell walls; wherein the electrodeis part of a fast-charging lithium ion cell that is configured to beoperated at a maximal charging rate of 4C or higher, and the activematerial particles are configured to incorporate and release lithiumions.
 2. The electrode of claim 1, wherein the electrode is an anode,with active material particles comprising at least one of Si, Ge and Sn,optionally at least partly coated and/or at least partly oxidized. 3.The electrode of claim 2, wherein the aerogel comprises any of copper,nickel and/or titanium, their combinations and/or their alloys.
 4. Theelectrode of claim 1, wherein the electrode is a cathode, with activematerial particles comprising primary cathode material nanoparticleswhich are single grains or are at groups smaller than
 10. 5. Theelectrode of claim 1 configured to be binder-free.
 6. The electrode ofclaim 1, further configured to have a form factor having a thicknessbetween 50 μm and 5 mm.
 7. The electrode according to claim 1, whereinthe wires or needles have widths of one to tens of nanometers andlengths of tens or hundreds of nanometers to one micrometer; and whereinthe cell walls have a thickness of one to tens of nanometers.
 8. Abattery comprising a fast-charging lithium ion cell with at least oneelectrode according to claim 2 as the anode thereof.
 9. The battery ofclaim 8, further comprising at least one cathode comprising cathodeactive material particles embedded in an electrically conductivemetallic porous structure.
 10. The battery of claim 9, wherein theelectrically conductive metallic porous structure of the at least onecathode comprises aerogel, the cathode active material particlescomprise primary cathode material nanoparticles which are single grainsor are at groups smaller than 10, the at least one cathode is configuredto be binder-free and has a specified form factor and be between 50 μmand 5 mm thick.
 11. The battery of claim 8, configured as a mono-cellbattery comprising only one anode and only one cathode and wherein theanode and the cathode are separated by a separator or by a semi-solidelectrolyte.
 12. The battery of claim 8, configured as any of Li-ion,Na-ion and/or Li—S battery or supercapacitor.
 13. A battery comprising afast-charging lithium ion cell with at least one electrode according toclaim 4 as the cathode thereof.
 14. The battery of claim 13, furthercomprising at least one anode with active material particles comprisingat least one of Si, Ge and Sn, optionally at least partly coated and/orat least partly oxidized, which are embedded in an electricallyconductive metallic aerogel.
 15. The battery of claim 14, wherein the atleast one anode is configured to be binder-free and have a specifiedform factor and be between 50 μm and 5 mm thick.
 16. The battery ofclaim 13, configured as a mono-cell battery comprising only one anodeand only one cathode and wherein the anode and the cathode are separatedby a separator or by a semi-solid electrolyte.
 17. The battery of claim16, configured as a cylindrical cell with the anode and the cathodepositioned longitudinally, parallel to an axis of the cell.
 18. Thebattery of claim 16, configured as a cylindrical cell with the anode andthe cathode positioned transversely with respect to an axis of the cell,the cathode contacting a cell cap and the anode contacting a cellbottom.
 19. A method of making an electrode comprising: embedding activematerial particles in an electrically conductive porous structure thatcomprises (a) an electrically conductive metallic aerogel that comprisesan anisotropic assembly of wires or needles, and (b) open-cell foamscomprising an anisotropic assembly of cell walls to yield an electrodeof a fast-charging lithium ion cell that is configured to be operated ata maximal charging rate of 4C or higher.
 20. The method of claim 19,further comprising configuring the electrode as an anode of afast-charging lithium ion cell, wherein the active material particlesare anode active material particles comprising at least one of Si, Geand Sn, optionally at least partly coated and/or at least partlyoxidized.
 21. The method of claim 19, further comprising configuring theelectrode as a cathode of a fast-charging lithium ion cell, wherein theactive material particles comprise primary cathode materialnanoparticles which are single grains or are at groups smaller than 10.22. The method of claim 19, further comprising: preparing a rawelectrode by the embedding of oxidized active material particles in theelectrically conductive metallic aerogel, and applying a dry etchingtreatment to the raw electrode to at least partly reduce the oxidizedactive material particles through pores of the electrically conductivemetallic aerogel to yield the electrode in an operable state.
 23. Themethod according to claim 19, wherein the wires or needles have widthsof one to tens of nanometers and lengths of tens or hundreds ofnanometers to one micrometer; and wherein the cell walls have athickness of one to tens of nanometers.